Clinical and neonatal outcomes of individually vitrified human sperm with Cryotop and Cell Sleeper

Technique for preserving limited number of human spermatozoa is important for successful treatment of patients with azoospermia and cryptozoospermia. This study determined whether the non-biological devices (Cryotop and Cell Sleeper) efficiently vitrify small numbers of human spermatozoa. From December 2011 to December 2018, 10 males with very low sperm numbers managed with a single sperm vitrification method. Post-warmed sperm recovery was similar with both devices. Post-warmed sperm motility and fertilization after intracytoplasmic sperm injection were significantly higher in Cryotop group than in Cell Sleeper group (40.0% vs. 22.0%, P < 0.01 and 50.7% vs. 21.7%, P < 0.01, respectively). The pregnancy rate was 15.4% and 2 healthy babies were born in the Cryotop, while 14.3% and 1 baby in the Cell Sleeper, which did not differ between the groups. Both devices have clinical advantages in terms of easy use and safety, and would be performed more efficiently by using devices with different properties.